Was October Revolution really a revolution or it was more of a coup?

This depends very much on your interpretation or point of view.

Let's use the French Revolution as an example. When does it begin? With the storming of the Bastille? This is an easy focal point, but there were forces moving long before the masses of Paris rose up, such as the bankruptcy of the Royal Treasury or the convening of the Estates General followed by the Constituent Assembly. At that point it was clear that the existing political system had to change (not necessarily be abolished by any means, just change), and there were all sorts of differing opinions on where it should go: Should the King abdicate in favor of a more worthy candidate? Who? Should the King grant more powers to the noble Parlement? Should there be a Parliamentary Monarchy? A constitutional Monarchy? What powers would the King retain, and which should be given over? Should powers be invested in a house of nobles, or an elected assembly? Who was eligible to stand, and who could cast votes? Should the Monarchy be abolished? To be replaced by what? If it was to be abolished, what should happen to the King?

As we know, the more time that passed, the more radical the change became. Not only would the Monarchy be overthrown, but the feckless Louis was to be executed along with his family and all the nobility the revolution could lay its hands on before setting to devouring its own children. I use the example to illustrate that a series of events while trying to grapple with massive sociopolitical change in a power vacuum while fighting both internal and external threats can be broadly labelled a Revolution. Whether or not the Thermidorian Reaction or the Coup of Brumaire or the Coup of Fructidor were individual coups or part of the overarching Revolution - to an extent - depend on where you consider the end of the Revolution. Was it when the Committee for Public Safety was decapitated? Was it when Napoleon was named First Consul? Emperor? Was defeated and exiled? The first or second time? Was the revolution still alive when Louis the XVIII was overthrown? When the Monarchy was again abolished? Has it ever ended?

Now contrast this with the Russian Revolution: When the French Revolution began there were no political parties as such. There were philosophical and debating clubs that transformed themselves into political action parties and radicalized alongside the revolution (or perhaps drove the radicalization?). Prior to the Russian Revolution there were political parties of all stripes with varying degrees of legitimacy and actual platforms for political change (the vast majority of which were underground and illegal as the Tsar held the absolute monopoly of political power). As the Revolution progressed, these parties and factions within parties opposed one another as to where the Revolution should head. For the Majority (Bolshevik) portion of the Marxist Russian Social Democratic Labour Party the end goal was always a radical, violent overthrow of any regime not committed to socialism and the dictatorship of the proletariat. Whether a Constitutional Monarchy or a Republic existed between the Tsar and the end goal was irrelevant. They were all just steps toward the inevitable Communist Utopia.

So, for the Russian Provisional Government (led by Alexander Kerensky - a moderate Socialist) October was a Coup d'Etat without doubt in that a bunch of radicals violently overthrew a legitimate government that had already transitioned from the autocracy of the Tsar and received international recognition, while the Bolsheviks always saw the Kerensky government as a temporary interlude between the status quo, and their version of the true international workers revolution. A quote attributed to Lenin is appropriate, "There are decades where nothing happens; and there are weeks where decades happen." For Lenin, Russia achieved the entirety of the French Revolution and then the Socialist Revolution between March and October of a single year.